Trigon, Jasmine and Nighthawk all have adjustability which makes them very versatile
In the following, I am comparing the three phono pre-amps in terms of adjustability of loads and gain.
Ray Samuels Nighthawk
Gain : 40db-75db adjustable in 6 increments
Input Impedance: 30, 50, 100, 500, 1k selectable (MC) & 47K (MM)
Input Capacitance: 220 pF (MM/MC) fixed
Trigon Vanguard II
Gain : 42 - 66 dB adjustable in 16 increments
Input Impedance: 47 KOhm fixed (MM), 25 to 1800 Ohm in 31 steps (MC)
Input Capacitance: 60 - 100 pF basic capacity / 47pF, 100pF, 147pF (selectable, important for MM)
Jasmine Audio LP2.0 mk II
Gain (fixed) : 55db (MM) and 70db (MC) at 1kHz
Input Impedance: 47 KOhm fixed (MM), 50/100/250/1K ohm selectable (MC)
Input Capacitance: 100 pF (MM/MC)
From the above, there is no doubt that the Trigon is the most versatile among the three. The wide range of input impedances makes these suitable for carts which have got low system impedance, such as Ortofon, and carts which are preferably terminated at higher impedances, such as Benz, Soundsmith etc. It is hard to find a phono pre-amp out there which is so versatile. Either the steps from low to high impedance are largish (Ray Samuels, Lehmann) or they are limited to low to medium impedances (Einstein) or medium to high impedances only.
Of course, being the most versatile may not guarantee the best sonics. However, it is one of the important things. I also came to know why Trigon was made this way. Actually this phono-stage was built for Ortofon. Ortofon needed to have such a versatile unit with small steps in load and gain for development of their carts. Later Trigon started marketing this with consent from Ortofon. The above is given to me by Jochen of course.
The Jasmine Audio LP2.0mkII is the least versatile among the three, but has a few absolutely superlative reviews as already pointed out by arj. I'll try and post some of those reports here later. The Ray Samuels Nighthawk has many reviews available from users and professional reviewers and they are generally very very good and also easy to find by googling. The Trigon is relatively unknown. German reviews are available and they are generally very good. The Trigon brand has been present in several audio shows, including Montreal 2011. I am just trying to dig up as much information as possible about these less known brands.
The Scheu site recommends both Lehmann and Trigon. In fact, one can buy these phono-stages directly from Scheu, or so it seems from their site.
Regards.